Throughout the world the re-use of hypodermic syringe products which are intended for single-use only is instrumental in drug abuse and in the transfer of contagious diseases. Intravenous drug users who routinely share and re-use syringes are a high-risk group with respect to the AIDS virus. Also, the effects of multiple use are a major concern in some countries where the repeated use of syringe products during mass inoculation programs may be responsible for the spread of many diseases. Syringes are often recycled in developing countries without proper sterilization.
Many attempts have been made to remedy this problem. Some designs involve the inclusion of structure which will allow the destruction or defeating of the syringe function through a conscious act by the user, such as breaking a syringe or one of its components. In addition, there are single-use hypodermic syringes which become incapable of further use automatically upon delivery of the medication without any additional act on the part of the user. Such syringes are taught in U.S. Pat. No. 4,961,728.
With single-use syringes using needle assemblies having a hub attached to a needle cannula there is a need to prevent the removal of the needle assembly after the use of the single-use syringe so that the needle assembly cannot be used again with other syringes. In addition to preventing the removal of the needle assembly, there is also a need for structure which will allow the easy attachment of the needle assembly to the syringe so that the needle assembly may be attached at the time of use and an appropriately sized needle may be used.